396 BIcKNELL: HAVE WE ENOUGH NEW ENGLAND BLACKBERRIES ? 
Rubus allegheniensis Porter. 
cuneifolius Pursh. 
frondosus Bigelow. 
nigricans Rydb. 
ispidus L. 
procumbens Mubhl. 
Baileyanus Britton. 
Enslenii Trat. 
flagellaris Willd. 
Under these names, if I hav e not wholly misconceived the prob- 
lem, all or nearly all more recent names may be disposed somewhat 
in accordance with the arrangement in the following tables. The 
problem is made very intricate by reason of the extreme varia- 
bility of the apparent hybrids, which would appear to have ac- 
quired a compound tendency to variation through their double 
inheritance. And th indications that compound hybrids have 
also to be reckoned with. What appear to be the product of the 
same crosses present themselves under many different aspects 
according as they resemble one or the other parent or variously 
combine the characters of both. And the crosses appear to reflect 
also the fluctuating forms of development to which the parents 
are subject under varied conditions of growth and in different 
parts of their range. So freely do our species appear to hybridize 
that there would seem to be little reason to doubt that every one of 
them holds the capability of crossing with every other one. There 
is thus among the species here enumerated, omitting Rubus cunet- 
folius, only a local plant in New England, a potentiality of forty- 
five primary hybrids, and nearly all of this possible number ap- 
pear to be accounted for by existing forms. Some of these seem to 
announce their parentage quite unmistakably, while others offer 
mere suggestions only, easily misinterpreted, of what their origin 
may be. The final word is not for the systematist but for the 
experimental culturist and must rest on the demonstration 
which induced crossing can alone supply. 
Not all of the species here taken to be valid are secure against 
the test, having its advocates, that species may not intergrade. 
